In recent years, demands for a high-resolution and high-quality video such as a high definition (HD) video and an ultra high definition (UHD) video have increased in various fields of applications. However, as video data has a higher resolution and higher quality, an amount of data or a bit rate of the video to be transferred increases more than existing video data. Accordingly, when video data is transferred using media such as existing wired or wireless broadband lines or is stored in existing storage media, the transfer cost and the storage cost thereof increase. High-efficiency video compressing techniques can be used to solve such problems.
Various techniques such as an inter prediction technique of predicting pixel values included in a current picture from a picture previous or subsequent to the current picture, an intra prediction technique of predicting pixel values included in a current picture using pixel information in the current picture, and an entropy coding technique of allocating a short codeword to a value of a high appearance frequency and allocating a long codeword to a value of a low appearance frequency are known as the video compressing techniques. It is possible to effectively compress and transfer or store video data using such video compressing techniques.